In a rotation preventive device for a scroll compressor, by forming a rotation preventive member for preventing a rotation of an orbiting scroll between a frame and an orbiting scroll or a fixed scroll and the orbiting scroll as a rectangular shape performable a sliding motion in a radial direction, it is possible to fabricate the rotation preventive member as small and light weight, accordingly the cost of materials can be reduced. In addition, by reducing abrasion between each key and each key groove, a stability of the orbiting scroll can be maintained, and by preventing a leakage of gas from happening, a reliability and an efficiency of a compressor can be improved and a noise of the compressor can be decreased.